If she is keeping it then I don't see why she should give them anything, she payed £1 for something she liked the look of, she wasn't to know what it was worth, if she did would she have payed £100 if that was the price ticket? Probably not.

If she was to sell it on then maybe she would donate some of the money to charity?

Most charity shops check things on ebay completed listings whilst pricing up, a lot of dealers go into these shops hoping to find a gem that's worth £1000's ( it's very rare to find anything ), I. Sure most of them would not donate what the item is really worth to the shop.

It would not occur to me to give the charity anything .I would simply count my blessings (and money) and maybe patronise it a bit more to give back by buying stuff.But as Frank has pointed out, most charity shops have experts they use to evaluate the stock before its put out and anything valuable is auctioned or sold to collectors.

It would depend on the charity. If it was a charity I felt I strongly wanted to support I would probably give them some of the money after selling the item, if it wasn't a charity I felt strongly about supporting I wouldn't feel obliged to give them anything.

Even more brutal, MIL works in a large charity warehouse - we give her a list, she pays shop floor prices for things but they never hit the shop window. Unfair, but those are the perks of the charity worker

So hard.5k would make an enormous difference to us -like really big.But I would feel guilty to keep it all.

Some would definitely go to a good cause.

I always tell people at a jumble sales if they're undercharging if I can see that at the point of purchase.Perhaps its acceptable to keep some if you didn't realise at the point of purchase in a charity shop that it was valuable.

I would do some soul searching and conscience wrestling, without wanting to do my family out if a bit of good fortune.